Biodiesel refers to a diesel-equivalent processed fuel consisting of short chain alkyl (methyl or ethyl) esters, made by transesterification of vegetable oils or animal fats, which can be used (alone, or blended with conventional diesel fuel) in unmodified diesel-engine vehicles.
On Aug. 31, 1937, G. Chavanne of the University of Brussels (Belgium) was granted a patent for a ‘Procedure for the transformation of vegetable oils for their uses as fuels’ (fr. ‘Procédé de Transformation d'Huiles Végétales en Vue de Leur Utilisation comme Carburants’) Belgian Patent 422,877. This patent described the alcoholysis (often referred to as transesterification) of vegetable oils using ethanol (and mentions methanol) in order to separate the fatty acids from the glycerol by replacing the glycerol with short linear alcohols. This appears to be the first account of the production of what is known as ‘biodiesel’ today.
The common international standard for biodiesel is EN 14214.
There are additional national specifications. ASTM D 6751 is the most common standard referenced in the United States and Canada. In Germany, the requirements for biodiesel are fixed in the DIN EN 14214 standard and in the UK the requirements for biodiesel is fixed in the BS EN 14214 standard, although these last two standards are essentially the same as EN 14214 and are just prefixed with the respective national standards institution codes.
There are standards for three different varieties of biodiesel, which are made of different oils:                RME (rapeseed methyl ester, according to DIN E 51606)        PME (vegetable methyl ester, purely vegetable products, according to DIN E 51606)        FME (fat methyl ester, vegetable and animal products, according to DIN V 51606)        
The standards ensure that the following important factors in the fuel production process are satisfied:                Complete reaction.        Removal of glycerin.        Removal of catalyst.        Removal of alcohol.        Absence of free fatty acids.        Low sulfur content.        
Whilst the conventional methods and apparatus for the production of biodiesel are adequate, they are typically large, on grid, complex, fixed chemical processing facilities, requiring a large number of staff to operate the facility and also transport costs and like to move the biodiesel to the end user. Alternatively, on a smaller scale they are batch processors that require on grid or external energy input and in infrastructure to house the system.
It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country.